Key points:

Tourism is the biggest contributor to the total asset value making up $29 billion

But tourist figures are down 50 per cent in the Whitsundays — operators say "this is as bad as it was during the GFC"

Deloitte Access Economics has calculated the economic, social and iconic value of the world heritage site in a report commissioned by the Great Barrier Reef Foundation.

Tourism is the biggest contributor to the total asset value making up $29 billion.

The Great Barrier Reef generates 64,000 jobs in Australia and contributes $6.4 billion dollars to the national economy, the report said.

It states the brand value, or Australians that have not yet visited the Reef but value knowing it exists, as $24 billion.

Recreational users including divers and boaters make up $3 billion.

"That's more than 12 Sydney Opera Houses, or the cost of building Australia's new submarines. It's even more than four times the length of the Great Wall of China in $100 notes," the report states.

The report does not include quantified estimates of the value traditional owners place on the Great Barrier Reef and it said governments should consider doing more to protect it.

Climate change remains biggest threat

It also references the back to back coral bleaching events which have devastated the reef and says climate change remains the most serious threat to the entire structure.

"We have already lost around 50 per cent of the corals on the GBR in the last 30 years. Severe changes in the ocean will see a continued decline ahead of us," the report states.

"Today, our Reef is under threat like never before. Two consecutive years of global coral bleaching are unprecedented, while increasingly frequent extreme weather events and water quality issues continue to affect reef health," said Dr John Schubert AO, Chair of the Great Barrier Reef Foundation.